The present disclosure relates to latex compositions and methods of their preparation. In particular, the methods of the present disclosure employ a single solvent formulation for preparation of crystalline polyester latex via phase inversion emulsification (PIE).
Latex emulsions of polyester resins are currently produced using PIE process in which the resins are dissolved in dual solvents, namely methyl ethyl ketone (MEK) and isopropyl alcohol (IPA), neutralized with an appropriate base, and mixed with water to create a homogeneous water-in-oil (W/O) dispersion (water droplets disperse in continuous oil). Subsequently, additional water is added to invert this dispersion into self-stabilized oil-in-water (O/W) latex. Energy intensive processing of the latex is then used to remove virtually all traces of the organic solvents, and finally surfactant and other preservatives may be added to provide stable latex with relatively high solid content of polyester. In such latex production, the solvent removal process takes long cycle time due to the presence of the solvent IPA, as IPA is highly soluble in the water phase, which translates into high processing cost or high toner manufacturing cost.
Therefore, there exists a need to reduce the manufacturing cost while still maintain the same properties of the toner. There exists a need to develop a process of preparing latex to exclude the use of IPA from the manufacturing process.
Thus, there exists a need to reduce the manufacturing cost while still maintaining the same properties of the toner.